I remember a Northwestern admissions rep saying that Northwestern doesn't superscore the ACT, but only looks at the highest Composite score. But later he said that they take best the writing score with the best Composite score.
This means if you get Composite 34, writing 8; and Composite 32, and writing 10; then it looks like Composite 34, writing 10.
Does anyone know if this is what other schools will do? I know most schools don't superscore the ACT subscores.